As the capability and capacity of CATV transmission and receiving systems increase, so does the need for connection means between the two which minimize signal loss.
Conventional CATV signals are transmitted via coaxial cable generally characterized by inner and outer conductors. The inner and outer conductors are separated by a dielectric insulator and externally covered by an outer jacket constructed of a weather and impact resistant material, such as rubber. Coaxial transmission cables must be connected either to another coaxial cable or a mating post or terminal on a receiving device such as a television. Numerous connectors have been devised to obtain such a mechanical and electrical connection.
Typical connectors comprise a pair of tubular elements coaxially extending from the body of a connector fitting. During attachment to the coaxial cable end, the outer conductor of the cable is received within the outer tubular element ("outer sleeve") of the connector. Simultaneously, the inner tubular element ("inner sleeve") of the connector is forced between the dielectric and the outer conductor of the cable end. Subsequently, the outer sleeve of the connector is constrictively crimped for fixation to the cable end.
Historically, infiltration of moisture or other environmental elements and poor connection of opposing conducting surfaces have been the most significant sources of signal loss. Until recently, hexagonal crimp configurations were most commonly used to attach connectors to cable ends. This type of crimp often failed to provide a uniform seal around the periphery of the connector, thereby resulting in a gap between connector and cable jacket. Moisture and/or dust could then be introduced into the conductive portion of the connector. Similarly, infiltration of moisture occurs because of the necessarily loose fit of a connector nut on the body of the connector. The connector nut allows the screwing of the connectorized cable end onto a mating connector.
Poor connection between conductive aspects of mating connectors is equally detrimental to signal integrity. For example, if the connector is not fastened securely to its mating connector, there will not be optimum conductive contact between the respective ground conductors of the respective coaxial cables. Such poor connection results in signal distortion. Less than optimum connection can also occur by the loosening of the connectors due to vibration, repeated change in environmental conditions, etc.
Recent improvements in connector technology have addressed these problems. So-called "compression" crimps are gaining wide acceptance in the CATV industry as a means for drastically limiting the amount of moisture, etc., that leaks into the cable end of a connector. A compression crimp deforms the outer sleeve of the connector essentially uniformly around its periphery. Such uniform compression assures that the outer sleeve engages the pliable outer jacket of the coaxial cable without gaps between the connector and cable end. Additionally, inner walls of connector outer sleeves now typically incorporate mechanisms for enhancing the post-crimp sealed engagement between outer sleeve of conductor and outer jacket of cable end.
Further improvements in connector performance relate to the implementation of an O-ring within the nut portion of the connector. U.S. Pat. No. 5,083,943 (the '943 patent) employs two separate O-rings. These O-rings formed of a pliable material resistant to and recoverable from deformation, such as rubber provide an improved barrier from external agents which could compromise connector performance. One of the O-rings of the '943 patent is sandwiched between the fixed inner and turnable outer ("nut") portion of the connector. The second O-ring of the '943 patent is captively seated in a groove proximate to the termination of the screw-receiving grooves on the inner portion of the nut portion of the connector. The second O-ring exerts an opposing force against the mating connector when compressed, as during engagement of mating connectors. This force is easily overcome during the process of engagement and encourages continued engagement between threaded and thread receiving aspects of opposing mating connectors.
One notable problem exists with the position of the second O-ring of the '943 patent. The opposing force resulting from compression of the O-ring also encourages separation between the attached connectors and threatens to diminish connective contact between the inner, conductive portions of the respective connectors and cables.
As such, there is a need for an end connector for coaxial cable which provides an essentially element-proof connection between coaxial cable ends. Additionally, there is a need for such connector wherein such weatherproofing does not adversely affect the electrical conduction characteristics of the connector. There is a further need for a connector in which the weatherproofing elements, themselves, maximize the electrical conduction characteristics of the connectors.